When you upvote someone's post or comment, the arrow turns solid color, and the $0.00 amount goes up a little. The amount it goes up is determined by the STEEM POWER that voter has, and how much % of voting is given..

You already gotten 6 votes - accumulating $1.09

look at my comment... there is a green arrow and a $0.00 Reply Edit line
click on the arrow to give me an upvote... and see the $0.00 increase (assuming you have sufficient voting power)